- A large, elongated dune lying parallel to the prevailing wind direction. Longitudinal dunes usually have symmetrical cross sections. They generally form in areas that are located behind an obstacle where sand is abundant and the wind is constant and strong. They are usually tens of meters high and up to 100 km (62 mi) long. Compare transverse dune.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.